92
An Urban Experience
Electrocardiogram (ECG):
An ECG should be performed as soon as possible. There are only 4 arrhythmias seen in cardiopulmonary arrest:
1. Asystole: Most common form seen in dogs and cats. CPR should be performed as normal.
2. Ventricular fibrillation (VF): VF is described by continuous irregular ventricular waveforms which represents the fluttering of the heart. Treatment of
VF is defibrillation with a defibrillator. If this is not available, precordial thump may convert the rhythm. Precordial thump involves applying large amount of force rapidly over the heart (almost like a punch!). If this is not successful, lidocaine may be administered. The aim of treatment of VF is to convert it into asystole.
3. Pulseless ventricular tachycardia: This is when the ECG looks like VT, however there is no heartbeat. This is treated the same as VF.
4. Pulseless electrical activity (PEA): This includes any wave forms (including normal sinus rhythm), with no heartbeat. This is treated the same as asystole.
Defibrillation is performed with a defibrillator. The defibrillator is set at 2 -3 J/kg and plenty of conduction gel is applied to both defibrillator paddles. When a cycle of compressions is completed, the animal is placed
in dorsal recumbency, and the paddles are held over both sides of the thorax. The person performing the defibrillation yells “clear!” ensuring no one is touching the table or animal before defibrillation is performed. Commence compressions immediately.
Fluids:
Fluids should be administered in hypovolaemic patients. If the animal died of cardiac reasons, fluids should not be administered, however after each drug is administered,
a small bolus (5 – 20 mL in total) of fluids should be administered. There is no ideal dose of fluids, however the author uses 20 mL/kg of Hartmann’s or CSL as quickly as possible. Hypertonic saline is also a good choice as it increases the intravascular volume quickly, and it reduces cerebral oedema which commonly occurs during cardiac arrest
Cause of arrest:
The following is a list commonly used in human medicine called the 6 Hs (hypovolaemia, hypoxaemia, hydrogen ion (acidosis), hypo/hyperkalaemia, hypothermia, hypoglycaemia) and 6 T (tachy/bradycardia, toxins, tamponade (cardiac), tension pneumothorax, thrombosis, trauma).
Identification of return of spontaneous circulation (ROSC):
ROSC can be identified by palpable pulses when compressions are not performed, and confirmed by auscultation of the heart. ROSC can be suspected if ETCO2 increases above 35 mmHg. A normal ECG trace does not mean there is ROSC, as the rhythm may be PEA as discussed above.
Post CPR care:
ECG, SpO2, ETCO , blood pressure, temperature, PCV/ 2
TS, electrolytes, and blood gas should be monitored. The animal may need to remain intubated and ventilation if hypoventilating.
After CPR, it is important to debrief with the team to improve team moral. It is also important to discuss what went well, and what could be improved to improve CPR in future patients.
References are available upon request.
42ND WORLD SMALL ANIMAL VETERINARY ASSOCIATION CONGRESS AND FECAVA 23RD EUROCONGRESS